Many people think frozen vegetables are less nutritious than fresh vegetables, but studies have shown that both forms can contain similar amounts of vitamins and minerals.
Only about 1 in 10 American adults eat enough fruits and vegetables, so most nutrition experts recommend consuming more produce in any form.
Grocery store freezers are stocked with nutrient-dense peas, broccoli florets, corn, and carrots. These convenient, pre-cut vegetables have a longer shelf life and, typically, a lower price point than fresh versions.
“Fresh and frozen are generally nutritionally similar and comparative. I would focus on what works best for you and your family based on things like cost, convenience, and personal preference, with the major goal being to increase overall vegetable intake,” Michael Laguros, MS, RD, a registered dietitian and extension program specialist at Texas A&M AgriLife Extension Service, told Verywell.
How Frozen Vegetables Stay Healthy
Vegetables contain important nutrients, like fiber, potassium, and vitamins A and C, and can help protect the body from heart disease and cancer. Commercially available frozen vegetables are harvested at peak ripeness, blanched, and frozen quickly in a process that preserves nutritional quality.
“Essentially, most frozen vegetables are blanched—either by submersing in boiling water or [being] passed through steam—to stop enzymes from continuing to ripen the product or otherwise degrade the product over time,” Carolyn Slupsky, PhD, a professor in the departments of nutrition and food science and technology at the University of California, Davis, told Verywell in an email.
Blanching is a key process that helps destroy some bacteria on the vegetables and deactivates enzymes that would otherwise harm the vegetable’s nutritional content, texture, and flavor. After blanching, vegetables are placed in an ice bath to stop the cooking process, drained, dried, and frozen.
Food scientists have determined the optimal amount of blanching time for different vegetables to ensure minimal nutrient loss and inactivation of enzymes while making sure not to cook the vegetables, according to Slupsky. Cauliflower florets take 3 minutes in boiling water, while onion rings only need 10 to 15 seconds.
“If you were to eat the vegetable right after it is harvested, it might have better nutrition, but most frozen vegetables have minimal nutrient losses after processing, so I would not worry so much about them having lower nutrition than fresh,” said Slupsky.
Frozen Vegetables Are Processed, But That’s Not a Bad Thing
Anyone concerned about processed foods might wonder if they should avoid frozen vegetables due to the processing involved in getting these products to the grocery store.
“I can see how the advice to avoid processed food can be confusing because unless you’re eating a completely raw diet, every food you consume has to be processed,” Sara Elnakib, PhD, MPH, RDN, a registered dietitian, department chair, and associate professor in the department of family and community health sciences at Rutgers University, told Verywell in an email.
Ultra-processed foods undergo multiple industrial-level manufacturing techniques and are enhanced with additives, like colors and sweeteners, before the highly-palatable products arrive on store shelves. Research has linked ultra-processed foods with a higher risk of cancer, cardiovascular disease, and death, but not all processed foods come with the same risks.
“Think of that chip that looks nothing like the potato it came from, or that soup mix that transforms when you add water. These foods tend to contain multiple ingredients and substances that are linked to unhealthy diet,” Elnakib said.
Frozen vegetables, however, don’t come with the same health risks. These are minimally processed to remove inedible parts and extend their shelf life, and this level of processing, unlike ultra-processing, does not drastically change the original product and is not linked to negative health outcomes.
“If we are thinking about freezing produce, it can actually maintain nutritional quality by delaying the decaying process that fruits and vegetables naturally go through after being harvested,” Elnakib said. “Sowing the decay process reduces the potential loss of important water-soluble vitamins like vitamins C and B complex, which are often more sensitive to things like heat and can oxidize with the passage of time.”
What to Consider When Buying and Storing Frozen Vegetables
Freezing helps preserve the nutritional quality of produce since many fresh vegetables start to lose nutrients after harvesting. If you want to freeze your own vegetables, it is important to start this process shortly after buying or picking the fresh produce instead of throwing those forgotten carrots or half-eaten bags of spinach from the back of your refrigerator into the freezer in an attempt to revive the vegetables.
“You can’t take a bad product and make it better by freezing. If fruits and vegetables are spoiled, freezing isn’t going to help; it’s just going to make things worse,” Kelly Kunkel, MS, a health and nutrition educator at the University of Minnesota Extension, told Verywell. “You want to start with a good quality, ripe product that would be something you would eat.”
Whether you decide to freeze your own vegetables or purchase pre-frozen produce, it is important to keep an eye out for ice crystals in the package, which might indicate that the vegetables were mishandled or kept in a freezer with temperature fluctuation issues.
“In freezing, most quality and nutritional loss can happen due to recrystallization, a process in which the product goes through freeze-thaw cycles,” Kumar Mallikarjunan, PhD, a professor of food engineering, food science, and nutrition at the University of Minnesota and a member of the refrigerated & frozen foods division at the Institute of Food Technologists, told Verywell in an email.
Frozen vegetables can stay in the freezer for about eight to twelve months when stored at a consistent 0 degrees Fahrenheit or lower. However, leaving the freezer door open for a long time or taking frozen vegetables in and out of the freezer can lead to the freeze/thaw cycles that destroy the quality and nutritional value of frozen produce, according to Mallikarjunan.
But, if vegetables are blanched, frozen, and stored properly, this is a better way to maintain nutritional quality than any other preservation method.
“Nutrients in the food deteriorate with time and temperature. By lowering the temperature, these reactions become slower, and we can preserve them through freezing,” Mallikarjunan said.